Another snippet, this from what I wrote just the other day, so it's in Book 4. I like the way it turned out.
Book 3 Chapter 2 will come out later this evening.
Then it happened. It was like passing backward through a sheer waterfall, not of water but of fire. The sensation poured over Jimmy in an electric wave, sharp and shocking, overwhelming and paralyzing him. Then he was through, and the cosmic vastness of Castiel surrounded him.
Angels were...huge. Somehow, even after thirteen years of living with one, Jimmy had never quite grasped this. But Castiel--injured, crippled, imprisoned Castiel--was unimaginably immense. Possessing him was like possessing a skyscraper, one that existed on all dimensions, most of them inaccessible to humans. Being trapped in Jimmy must be incredibly confining for Castiel, like a phoenix whose wingspan stretched from horizon to horizon somehow being crammed into a shoebox.
And now Jimmy, fragile creature of dust and clay, had propelled himself into this colossal space. The expansion stretched his mind almost to the breaking point. It would have broken other minds, he knew with no sense of ego, only acknowledgement of fact. There were reasons that he was fit to be an angelic vessel. One of them was his ability to bear this, no matter how narrowly.